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Telomere length associated with racial bias, discrimination

May 21, 2014

Shorter leukocyte telomere length is associated with earlier mortality and has also been tied to many age-related health issues, such as heart disease, diabetes, dementia, Alzheimer’s disease, and arthritis.

NIA is dedicated through research to eliminating health inequities among older adults. The Institute funds studies to identify disparities, understand how social disadvantage impacts disease processes, develop effective interventions to address these issues, and translate research in clinical settings and beyond.

Health disparities studies may appear directly relevant in neuroscience (including Alzheimer’s research), geriatrics and clinical gerontology, and the behavioral and social sciences; but research into health disparities at the basic biological level is harder to define. Deep within our cells—beyond genetic predispositions for health issues—don’t we all age in the same way?

“In a field dominated by studies using animal models, it can be more difficult to find the health disparities connection,” said Dr. Felipe Sierra, director of NIA’s Division of Aging Biology. “And yet, biology of aging research is evolving, especially with the growth of geroscience. We are finding new opportunities to investigate how race and ethnicity, as well as disparities among special populations, might affect aging at the most basic molecular and cellular levels.”

Connecting biological aging to health disparities

One recent NIA-funded investigation illustrates how basic studies can inform what we know about health disparities. In a study of 92 African American men aged 30-50, those who demonstrated a stronger implicit anti-black bias and reported higher levels of racial discrimination had the shortest leukocyte telomere length (LTL). Led by Dr. David H. Chae at the University of Maryland, the report, “Discrimination, Racial Bias, and Telomere Length in African American Men,” was published February 2014 in the American Journal of Preventative Medicine.

Telomeres are a stretch of DNA at each end of a chromosome that protects the protein-encoding part of the DNA. They become shorter each time a cell divides. When a telomere becomes too short, it can no longer protect the cell’s DNA, leaving the cell at risk for serious damage. Telomere length is an indicator of biological aging; shorter LTL is associated with earlier mortality. It also has been tied to many age-related health issues, such as heart disease, diabetes, dementia, Alzheimer’s disease, and arthritis.

“Shorter telomeres also have been associated with experiences of heightened psychosocial stress and exposure to adverse social conditions,” said Dr. Lis Nielsen, chief of the Individual Behavioral Processes Branch in NIA’s Division of Behavioral and Social Research, and program officer for this research. “Dr. Chae’s co-author, Dr. Elissa Epel, has proposed LTL as a ‘psychobiomarker’ of aging, a link between psychological stress and health.”

The association between LTL and anti-black bias and racial discrimination identified in this study was found after controlling for chronological age and socioeconomic and health-related characteristics, including 22 common diseases, smoking status, and waist-hip ratio.

Study design and results

In the study, scientists measured in-group racial bias using a test that gauges unconscious racial attitudes based on the speed with which a participant matches facial images with words that have positive and negative connotations. Personal experience with discrimination was determined using a questionnaire; telomere length was measured from a dried blood spot sample.

Researchers found that individually, neither discrimination nor racial bias had a clear association with LTL. Rather the combination, or interaction, of the two factors was significant.

“We saw that those participants who internalize negative racial group attitudes—have an anti-black bias—may be more likely to perceive they deserve discrimination and have shorter telomeres,” said Dr. Chae. “Those who feel positively about their race—have a pro-black bias—appear to be protected in some way.”

The investigators noted several limitations to their study. More research is needed to explain the connection between bias, discrimination, and telomere length. Also, generalizability of the findings is limited given the small study group.

“Despite its caveats, this investigation supports a promising direction for measurement and research to better understand health disparities, in this case in African American men,” said Dr. Carl V. Hill, director of NIA’s Office of Special Populations. “This approach, one that accounts for psychosocial factors and is rooted in the basic biology of aging, is very exciting.”